Colorectal cancer among younger people in rising across the world. A new study published this week shows Switzerland is no exception. About seven in 100,000 people under 50 are diagnosed annually. and the trend is moving in the wrong direction.
The study by researchers at the University of Geneva and Geneva’s University Hospital analysed nearly 100,000 cases between 1980 and 2021 and described the increase as “alarming”. Over that period, incidence among those under 50 rose by around 0.5% a year—0.46% in men and 0.49% in women. Cases are now appearing in people in their thirties with no personal or family history.
The pattern contrasts with older age groups. Among those over 50, incidence has declined since the 2000s, a trend widely attributed to screening and early detection—cancer precursors can be detected and removed.
A gap in screening
Younger adults are largely excluded from routine screening. In Switzerland, health insurers cover colorectal-cancer screening from age 50. The study’s authors argue that prevention strategies should be adjusted, including earlier screening and greater awareness of symptoms among younger people.
Diagnosis also tends to come later. Among patients under 50, 27.7% are diagnosed at stage IV, when the cancer has already spread. The comparable figures are 22.1% for those aged 50–74 and 19.4% for those over 75.
This reflects a structural problem rather than more aggressive disease. Because colorectal cancer is seen as an illness of those over 50, symptoms such as blood in the stool or abdominal pain are often attributed to benign causes in younger patients, delaying diagnosis.
Changes in diet a leading hypothesis
The reasons for the rise are not yet fully understood. Researchers increasingly point to the gut microbiome and earlier exposures to infections or antibiotic use, which may shape risk decades before diagnosis.
Diet is one likely factor. Fibre intake—closely linked to a healthy gut microbiome—is low in Switzerland. About 87% of people in Switzerland consume less than recommended levels; among younger adults the share exceeds 90%, and intake is further from the target. Fibre is in unrefined plants. Diets high in meat, dairy, eggs and processed foods can easily contain almost no fibre. The recommended daily intake is 30g. A CHF 1 can of beans delivers half of this.
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Study (in English)
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